1. Field of the Invention
This invention relates to integrated circuits, and more particularly, to thermal control of integrated circuits.
2. Description of the Related Art
During the design of a processor or other type of integrated circuit (IC), many factors must be considered. Typically, factors such as performance are balanced with other factors such as power consumption. Another factor that affects the design of many IC's is thermal output. Many IC's may generate a significant amount of heat during operation. Left unchecked, the heat generated during operation of an IC can cause damage or complete failure.
To prevent heat-related damage, many IC's employ some form of thermal control apparatus. In various embodiments, a thermal control apparatus in an IC may include one or more temperature sensors at various locations, and a control unit. The control unit may receive temperature indications from the various sensors, and compare these indications to one or more temperature thresholds. In the event that the temperature reported from one of the temperature sensors exceeds a threshold, operation of the IC may be scaled back to prevent further temperature increases. Scaling back the performance of the IC may be accomplished by reducing a supply voltage provided thereto, reducing a clock frequency, both, or by some other method (e.g., reducing, limiting, or re-allocating a workload of the IC). The IC may be held in the reduced performance state until the temperature falls below the threshold, and additionally for a period of time thereafter.
The temperature threshold at which performance is reduced may be based on a parameter known as thermal design power (TDP), which may be defined as the amount of power that may be dissipated by the IC (or cooling system thereof) without exceeding a specified maximum temperature of the IC itself. TDP may be set based on a specified ambient temperature. For example, the TDP of an IC may be specified for an ambient temperature of 35° C. That is, power consumption may be enabled up to an amount that would cause overheating (as determined by the maximum specified IC temperature) at an ambient temperature (e.g., room temperature) of 35° C. The maximum temperature may thus be specified as a temperature on the IC die in which TDP can no longer be dissipated. Power consumption, and thus performance may thus be reduced when this temperature is reached.